An energy storage device, especially a lithium secondary battery, has been widely used recently for a power source of a small-sized electronic device, such as a mobile telephone, a notebook personal computer, etc., and a power source for an electric vehicle or electric power storage. With respect to a thin electronic device, such as a tablet device, an ultrabook, etc., a laminate-type battery or a prismatic battery using a laminate film, such as an aluminum laminate film, etc., for an outer packaging member thereof is frequently used. In such a battery, the outer packaging member is thin, and therefore, there is involved such a problem that the battery is easily deformed even by a bit of expansion of the outer packaging member and the deformation very likely influences the electronic device.
A lithium secondary battery is mainly constituted of a positive electrode and a negative electrode, each containing a material capable of absorbing and releasing lithium, and a nonaqueous electrolytic solution including a lithium salt and a nonaqueous solvent; and a carbonate, such as ethylene carbonate (EC), propylene carbonate (PC), etc., is used as the nonaqueous solvent.
In addition, a lithium metal, a metal compound capable of absorbing and releasing lithium (e.g., a metal elemental substance, a metal oxide, an alloy with lithium, etc.), and a carbon material are known as the negative electrode of the lithium secondary battery. In particular, a nonaqueous electrolytic solution secondary battery using, as the carbon material, a carbon material capable of absorbing and releasing lithium, for example, coke or graphite (e.g., artificial graphite or natural graphite), etc., is widely put into practical use.
Since the aforementioned negative electrode material stores and releases lithium and an electron at an extremely electronegative potential equal to the lithium metal, it has a possibility that a lot of solvents are subjected to reductive decomposition, and a part of the solvent in the electrolytic solution is reductively decomposed on the negative electrode regardless of the kind of the negative electrode material, so that there were involved such problems that the movement of a lithium ion is disturbed due to deposition of decomposed products, generation of a gas, or expansion of the electrode, thereby worsening battery characteristics, such as cycle properties, etc., especially in the case of using the battery at a high temperature and at a high voltage; and that the battery is deformed due to expansion of the electrode. Furthermore, it is known that a lithium secondary battery using a lithium metal or an alloy thereof, a metal elemental substance, such as tin, silicon, etc., or a metal oxide thereof as the negative electrode material may have a high initial battery capacity, but the battery capacity and the battery performance thereof, such as cycle properties, may be largely worsened because the micronized powdering of the material may be promoted during cycles, which brings about accelerated reductive decomposition of the nonaqueous solvent, as compared with the negative electrode formed of a carbon material, and the battery may be deformed due to expansion of the electrode.
Meanwhile, since a material capable of absorbing and releasing lithium, which is used as a positive electrode material, such as LiCoO2, LiMn2O4, LiNiO2, LiFePO4, etc., stores and releases lithium and an electron at an electropositive voltage of 3.5 V or more on the lithium basis, it has a possibility that a lot of solvents are subjected to oxidative decomposition especially in the case of using the battery at a high temperature and at a high voltage, and a part of the solvent in the electrolytic solution is oxidatively decomposed on the positive electrode regardless of the kind of the positive electrode material, so that there were involved such problems that the resistance is increased due to deposition of decomposed products; and that a gas is generated due to decomposition of the solvent, thereby expanding the battery.
Under such a situation, in electronic devices having a lithium secondary battery mounted therein, the electric power consumption increases, and the capacity increases steadily. The electrolytic solution is in the environment where the decomposition is apt to take place more and more due to an increase of temperature of the battery by the heat generation from the electronic device, an increase of voltage of charging setting voltage of the battery, and the like. Thus, there was involved such a problem that the battery becomes unable to be used due to expansion of the battery caused by the gas generation, actuation of a safety mechanism to cut off the current, etc., or the like.
Irrespective of the foregoing situation, the multifunctionality of electronic devices on which lithium secondary batteries are mounted is more and more advanced, and the electric power consumption tends to increase. The capacity of the lithium secondary battery is thus being much increased, and because of an increase of a density of the battery, a reduction of a useless space capacity within the battery, and so on, a volume occupied by the nonaqueous electrolytic solution in the battery is becoming small. In consequence, it is the present situation that in the case of using the battery at a high temperature and at a high voltage, the battery performance is apt to be worsened by decomposition of a bit of the nonaqueous electrolytic solution.
PTL 1 discloses dihydro-furo[3,4-d]-1,3-dioxole-2,4,6-trione as one of bicyclo compounds and suggests that when added to an electrolytic solution, the electrochemical characteristics of the battery, especially the cycle capacity retention rate at 55° C., is improved.
PTL 2 discloses diethyl 2-oxo-1,3-dioxolane-4,5-dicarboxylate having tetraethylammonium tetrafluoroborate dissolved therein as an electrolytic solution.
PTL 3 suggests that when an electrolytic solution containing methacryloxymethyl ethylene carbonate is used, even in the case of using high-crystalline carbon for a negative electrode, the reductive decomposition of the solvent is inhibited, and the charging and discharging efficiency is improved.
PTL 4 proposes a nonaqueous electrolytic solution containing a cyclic sulfuric acid ester, such as an ethylene glycol sulfuric acid ester, etc., and describes that the decomposition and deterioration of the electrolytic solution on the electrode surface are inhibited.
PTL 5 proposes a nonaqueous electrolytic solution containing ethylene sulfite and vinylene carbonate and describes that the 25° C. cycle characteristics are improved.
PTL 6 proposes a nonaqueous electrolytic solution containing a cyclic ether compound, such as 1,3-dioxane, 1,3-dioxolane, etc., and describes that a reaction of a positive electrode with the electrolytic solution at a high temperature is inhibited, so that the safety is improved.
PTL 7 proposes a nonaqueous electrolytic solution containing 1,5,2,4-dioxadithiepane 2,2,4,4-tetraoxide and suggests that the cycle characteristics and storage characteristics are improved.
PTL 1: US 2012/0088160A
PTL 2: JP-A 7-285960
PTL 3: JP-A 2000-40526
PTL 4: JP-A 10-189042
PTL 5: JP-A 11-121032
PTL 6: JP-A 2014-72050
PTL 7: JP-A 2004-281368